Flatworm get most of their oxygen through diffusion.
Destruction of myelin will affect the nerve and there will be the less conduction of electrical impulses from the brain to other parts of the body and the nerve signal sent to the brain are delayed. These damaged nerve areas form sclerosis which disrupts the signalling capacity of the nerve. This may occur due to genetic defects, infectious agents, auto immune reactions and trauma.
Answer:d) contracting her pupils and increasing secretion of stress hormones.
Explanation:
Peripheral nervous system consists of 3 major neuronal levels: vegetative (reticular formation and brain stem), limbic system and neocortical level. The RAS is the link between the brain and the spinal cord.
Brain stem consists of pons, medulla oblongata and mesencephalon. Brain stem is responsible for involuntary functions such as heart beat, respiration and vasomotor activity. Limbic system represents the emotional control center. It consists of thalamus, hypothalamus and pituitary gland and maintains homeostasis. Neocortical part processes sensory information and regulates emotional responses.
Autonomic nervous system (ANS) regulates visceral activities and organs (circulation, digestion, respiration and temperature). ANS has two divisions: sympathetic and parasympathetic nervous system.Parasympathetic nervous system regulates homeostasis via the release of acetylcholine (Ach). Parasympathetic nervous system is responsible for energy conservation and relaxation.
There are three stages in the stress response: immediate effects of stress, intermediate effects of stress and prolonged effects of stress.
Vasoconstriction
Definition-The blood vessels under your skin become narrower. This decreases blood flow to your skin, retaining heat near the warm inner body.
